The documentation at https://backstage.forgerock.com/docs/idm/7/install-guide/about-ds-repo.html#about-ds-repo looks wrong: the default password of the embedded DS repo administrator now seems to be generated randomly.
Trying to use "password" just fails:
./dsconfig -p 34444 -w password -X -h localhost -D uid=admin
Unable to proceed, invalid credentials
One must document how to retrieve or at least change it, for example in order to be able to change the DS repo configuration (to enable error logs for example, that are disabled by default)